In its more radical phase, the French Revolution witnessed not only serious class conflict but also a vigorous attack on the Catholic Church and on Christianity itself. The Church was brought under state control, and members of the clergy were required to swear an oath of allegiance to the revolution. The revolutionary government closed many church buildings or sold them to the highest bidder. The government also seized church property to finance France’s wars. For a time, revolutionaries tried to establish a Cult of Reason to replace the Christian faith. This attack on the Church also involved the closure of monasteries and efforts to force priests to abandon their vocation and even to marry. Visual Source 16.3 suggests some of the reasons that ardent revolutionaries were so opposed to the supernatural religion in general and the Catholic Church in particular.